DIPHTHERIA - CHANGING PATTERNS IN THE DEVELOPING-WORLD AND THE INDUSTRIALIZED WORLD

In the past, diphtheria was considered one of the most serious childho od diseases because it took a heavy toll in health and life among pres chool-aged children. Prior to the widespread availability of diphtheri a toroid, nearly 70% of cases were in children younger than 15 years o f age. In the industrialized countries, immunization against diphtheri a became widespread in the 1940s and 1950s. This led to a marked decre ase in the incidence of diphtheria. There was also a decrease in circu lating toxigenic Corynebacterium diphtheriae organisms, resulting in l ess natural boosting of antibody levels. This has led to gaps in the i mmunity of the adult population. Since 1990, diphtheria has made a spe ctacular comeback in several European countries, with a high proportio n of cases in adults. In developing countries, immunization of infants with diphtheria toroid was introduced within the Expanded Programme o n Immunization in the late 1970s. Coverage rose slowly to 45% in 1985 and 79% in 1992. Because the pool of immunized persons is not yet larg e, the process of maintaining immunity still operates through natural mechanisms, including frequent skin infections caused by C. diphtheria e. But recently, several developing countries where coverage has been high for 5-10 years have reported diphtheria outbreaks. These outbreak s have been characterized by high case fatality rates, a large proport ion of patients with complications, and their occurrence in both young and older age groups. In all countries, priority should be given to e fforts to reach at least 90% coverage with three doses of diphtheria t oroid in children below one year of age, In countries where diphtheria has been successfully controlled, immunity levels should be maintaine d by booster doses.